OBJECTIVE: To investigate the effect of moxibustion on central insulin resistance related proteins of the rats suffering from diabetic cognitive decline, and analyze the underlying mechanism of moxibustion for cognition improvement. METHODS: Using the intraperitoneal injection of STZ combined with a high-fat diet, the rat model of diabetic cognitive decline were prepared. Twenty successfully-modeled rats were assigned randomly into a model group and a moxibustion group, 10 rats in each one. Besides, a blank group was set up with 10 rats collected. In the moxibustion group, suspending moxibustion was applied to "Baihui" (GV20), "Shenting" (GV24) and "Dazhui" (GV14) at the same time, 20 min in each intervention, once a day, and 6 interventions were delivered weekly and the duration of treatment was consecutive 4 weeks. The random blood glucose was measured using glucometer, and the learning-memory ability was detected by water maze test. HE staining was used to observe the morphology of neurons in the hippocampal tissue, real-time PCR assay was to detect mRNA expression of insulin receptor substrate 1 (IRS1), phosphatidylinositol 3-kinase (PI3K) and protein kinase B (AKT) in the hippocampal tissue. The Western blot method was employed to detect the protein expression of IRS1, PI3K, AKT, phosphorylated IRS1 (p-IRS1), phosphorylated PI3K (p-PI3K) and phosphorylated AKT (p-AKT) in the hippocampal tissue, and the ratio of p-IRS1/IRS1, p-PI3K/PI3K and p-AKT/AKT was calculated separately. The immunofluorescence intensity of p-IRS1, p-PI3K, and p-AKT was measured using immunofluorescence. RESULTS: Compared with the blank group, the rats of the model group exhibited higher random blood glucose (P<0.001), longer escape latency (P<0.001), severe pathological damage in the hippocampus, lower mRNA expression of IRS1, PI3K, and AKT (P<0.001), reduced ratio of p-IRS1/IRS1, p-PI3K/PI3K and p-AKT/AKT (P<0.001), and declined immunofluorescence intensity of p-IRS1, p-PI3K, and p-AKT in the hippocampal tissue (P<0.001). In comparison with the model group, for the rats of the moxibustion group, the random blood glucose decreased (P<0.05), the escape latency was shortened (P<0.01), the hippocampal pathological damage was attenuated, the mRNA expression of IRS1, PI3K and AKT increased (P<0.01), the ratio of p-IRS1/IRS1, p-PI3K/PI3K and p-AKT/AKT was elevated (P<0.01, P<0.05), and the immunofluorescence intensity of p-IRS1, p-PI3K, and p-AKT in the hippocampal tissue was strengthened (P<0.01, P<0.05). CONCLUSION In diabetic rats experiencing cognitive decline, moxibustion can enhance the learning-memory ability, which may be attributed to modulating the protein expression of IRS1, PI3K, and AKT, and their phosphorylation, activating insulin signal transduction, and reducing central insulin resistance.
Animals ; Moxibustion ; Insulin Resistance ; Rats ; Male ; Insulin Receptor Substrate Proteins/genetics* ; Rats, Sprague-Dawley ; Humans ; Proto-Oncogene Proteins c-akt/genetics* ; Cognitive Dysfunction/genetics* ; Diabetes Mellitus, Experimental/therapy* ; Hippocampus/metabolism* ; Acupuncture Points ; Phosphatidylinositol 3-Kinases/genetics*

OBJECTIVE: To elucidate the effect of Huanglian-Renshen-Decoction (HRD) on ameliorating type 2 diabetes mellitus by maintaining islet β -cell identity through regulating paracrine and endocrine glucagon-like peptide-1 (GLP-1)/GLP-1 receptor (GLP-1R) in both islet and intestine. METHODS: The db/db mice were divided into the model (distilled water), low-dose HRD (LHRD, 3 g/kg), high-dose HRD (HHRD, 6 g/kg), and liraglutide (400 µ g/kg) groups using a random number table, 8 mice in each group. The db/m mice were used as the control group (n=8, distilled water). The entire treatment of mice lasted for 6 weeks. Blood insulin, glucose, and GLP-1 levels were quantified using enzyme-linked immunosorbent assay kits. The proliferation and apoptosis factors of islet cells were determined by immunohistochemistry (IHC) and immunofluorescence (IF) staining. Then, GLP-1, GLP-1R, prohormone convertase 1/3 (PC1/3), PC2, v-maf musculoaponeurotic fibrosarcoma oncogene homologue A (MafA), and pancreatic and duodenal homeobox 1 (PDX1) were detected by Western blot, IHC, IF, and real-time quantitative polymerase chain reaction, respectively. RESULTS: HRD reduced the weight and blood glucose of the db/db mice, and improved insulin sensitivity at the same time (P<0.05 or P<0.01). HRD also promoted mice to secrete more insulin and less glucagon (P<0.05 or P<0.01). Moreover, it also increased the number of islet β cell and decreased islet α cell mass (P<0.01). After HRD treatment, the levels of GLP-1, GLP-1R, PC1/3, PC2, MafA, and PDX1 in the pancreas and intestine significantly increased (P<0.05 or P<0.01). CONCLUSION HRD can maintain the normal function and identity of islet β cell, and the underlying mechanism is related to promoting the paracrine and endocrine activation of GLP-1 in pancreas and intestine.
Animals ; Glucagon-Like Peptide 1/metabolism* ; Diabetes Mellitus, Type 2/metabolism* ; Glucagon-Like Peptide-1 Receptor/metabolism* ; Insulin-Secreting Cells/pathology* ; Drugs, Chinese Herbal/pharmacology* ; Male ; Blood Glucose/metabolism* ; Insulin/blood* ; Mice ; Intestinal Mucosa/pathology* ; Apoptosis/drug effects* ; Cell Proliferation/drug effects* ; Islets of Langerhans/pathology*

Parkinson's disease (PD), a chronic and common neurodegenerative disease, is characterized by the progressive loss of dopaminergic neurons in the dense part of the substantia nigra and abnormal aggregation of alpha-synuclein. Type 2 diabetes mellitus (T2DM) is a metabolic disease characterized by chronic insulin resistance and deficiency in insulin secretion. Extensive evidence has confirmed shared pathogenic mechanisms underlying PD and T2DM, such as oxidative stress caused by insulin resistance, mitochondrial dysfunction, inflammation, and disorders of energy metabolism. Conventional drugs for treating T2DM, such as metformin and glucagon-like peptide-1 receptor agonists, affect nerve repair. Even drugs for treating PD, such as levodopa, can affect insulin secretion. This review summarizes the relationship between PD and T2DM and related therapeutic drugs from the perspective of insulin signaling pathways in the brain.
Humans ; Parkinson Disease/drug therapy* ; Diabetes Mellitus, Type 2/pathology* ; Signal Transduction/physiology* ; Receptor, Insulin/metabolism* ; Animals ; Insulin Resistance/physiology* ; Insulin/metabolism*

Objective: To investigate the effect and mechanism of miR-96-5p on apoptosis of PC12 cells induced by maltol aluminum. Methods: In January 2021, PC12 cells at logarithmic growth phase were divided into blank control group and low, medium and high dose group. Cells in each group were treated with 0, 100, 200 and 400 μmol/L maltol aluminum for 24 hours respectively. Cells were collected and cell apoptosis rates were detected by flow cytometry, miR-96-5p and insulin receptor substrate 1 (IRS1) mRNA expressions were detected by qRT-PCR, and the protein expression levels of cysteine protease 3 (Caspase3) 、activated cysteine protease 3 (Cleaved-caspase3) 、IRS1、phosphorylated protein kinase B (p-AKT) and phosphorylated glucose synthesis kinase 3β (p-GSK3β) were detected by western blotting. The target binding relationship between miR-96-5p and IRS1 was detected by double luciferase reporter gene experiment. The miR-96-5p inhibitor cells and negative control cells were constructed after transfecting PC12 cells with miR-96-5p inhibitor for 24 hours. The cells were divided into blank control group, negative control group, aluminum exposure group, aluminum exposure+negative control group, aluminum exposure+miR-96-5p inhibition group, and miR-96-5p inhibition group. After transfecting PC12 cells with miR-96-5p inhibition and IRS1 siRNA for 24 h, the cells were divided into aluminum exposure+miR-96-5p inhibition+negative control group and aluminum exposure+miR-96-5p inhibition+IRS1 inhibition group. The control group was cultured in complete culture medium, and cells in the aluminum exposure group were treated with 200 μmol/L maltol aluminum for 24 hours. Cells in each group were collected and the apoptosis rate, miR-96-5p and IRS1 mRNA expression levels, as well as protein expression levels of Caspase3, Cleaved-caspase3, IRS1, p-AKT, and p-GSK3β were measured. Results: After 24 hours of exposure, compared with blank control group and low-dose group, the apoptosis rates, relative expressions of Caspase3 and Cleaved-caspase3 proteins, and relative expressions of miR-96-5p in the medium and high-dose groups of PC12 cells were significantly increased, while the relative expression levels of IRS1 mRNA, IRS1, p-AKT and p-GSK3β proteins were significantly decreased (P<0.05). Targetscan prediction and double luciferase report experiment both proved that IRS1 was a direct target gene of miR-96-5p. In the transfection experiment, compared with the aluminum exposure group, the apoptosis rate, the relative expressions of Caspase3 and Cleaved-caspase3 proteins, the relative expression of miR-96-5p in the aluminum exposure+miR-96-5p inhibition group were significantly decreased, while the relative expression levels of IRS1 mRNA and IRS1, p-AKT and p-GSK3β proteins were significantly increased (P<0.05). In the IRS1 low expression experiment, compared with the aluminum exposure+miR-96-5p inhibition+negative control group, the apoptosis rate, the relative expressions of Caspase3 and Cleaved-caspase3 proteins in the aluminum exposure+miR-96-5p inhibition+IRS1 inhibition group were significantly increased, while the relative expression levels of IRS1 mRNA and IRS1, p-AKT and p-GSK3β proteins were significantly decreased (P<0.05) . Conclusion: The increased expression of miR-96-5p and the targeted inhibition of IRS1 may be one of the mechanisms of apoptosis of PC12 cells induced by maltol aluminum exposure.
Animals ; Rats ; Aluminum/toxicity* ; Apoptosis ; Cell Proliferation ; Glycogen Synthase Kinase 3 beta/metabolism* ; Insulin Receptor Substrate Proteins/metabolism* ; MicroRNAs/metabolism* ; PC12 Cells ; Proto-Oncogene Proteins c-akt/metabolism* ; RNA, Messenger

OBJECTIVE: In this study, the combined effect of two stressors, namely, electromagnetic fields (EMFs) from mobile phones and fructose consumption, on hypothalamic and hepatic master metabolic regulators of the AMPK/SIRT1-UCP2/FOXO1 pathway were elucidated to delineate the underlying molecular mechanisms of insulin resistance. METHODS: Weaned Wistar rats (28 days old) were divided into 4 groups: Normal, Exposure Only (ExpO), Fructose Only (FruO), and Exposure and Fructose (EF). Each group was provided standard laboratory chow ad libitum for 8 weeks . Additionally, the control groups, namely, the Normal and FruO groups, had unrestricted access to drinking water and fructose solution (15%), respectively. Furthermore, the respective treatment groups, namely, the ExpO and EF groups, received EMF exposure (1,760 MHz, 2 h/day x 8 weeks). In early adulthood, mitochondrial function, insulin receptor signaling, and oxidative stress signals in hypothalamic and hepatic tissues were assessed using western blotting and biochemical analysis. RESULT: In the hypothalamic tissue of EF, SIRT1, FOXO 1, p-PI3K, p-AKT, Complex III, UCP2, MnSOD, and catalase expressions and OXPHOS and GSH activities were significantly decreased ( P < 0.05) compared to the Normal, ExpO, and FruO groups. In hepatic tissue of EF, the p-AMPKα, SIRT1, FOXO1, IRS1, p-PI3K, Complex I, II, III, IV, V, UCP2, and MnSOD expressions and the activity of OXPHOS, SOD, catalase, and GSH were significantly reduced compared to the Normal group ( P < 0.05). CONCLUSION The findings suggest that the combination of EMF exposure and fructose consumption during childhood and adolescence in Wistar rats disrupts the closely interlinked and multi-regulated crosstalk of insulin receptor signals, mitochondrial OXPHOS, and the antioxidant defense system in the hypothalamus and liver.
Humans ; Rats ; Animals ; Adult ; Rats, Wistar ; Fructose/metabolism* ; Catalase ; Receptor, Insulin/metabolism* ; AMP-Activated Protein Kinases/metabolism* ; Electromagnetic Fields/adverse effects* ; Sirtuin 1/metabolism* ; Cell Phone ; Phosphatidylinositol 3-Kinases/metabolism* ; Forkhead Box Protein O1/metabolism* ; Uncoupling Protein 2

OBJECTIVE: To explore the effect of curcumin on the insulin receptor substrate 1 (IRS1)/phosphatidylinositol-3-kinase (PI3K)/endometrial expression of glucose 4 (GLUT4) signalling pathway and its regulator, phosphatase and tensin homolog (PTEN), in a rat model of polycystic ovarian syndrome (PCOS). METHODS: PCOS model was induced by letrozole intragastric administration. Sprague-Dawley rats were randomized into 4 groups according to a random number table: (1) control group; (2) PCOS group, which was subjected to PCOS and received vehicle; (3) curcumin group, which was subjected to PCOS and treated with curcumin (200 mg/kg for 2 weeks); and (4) curcumin+LY294002 group, which was subjected to PCOS, and treated with curcumin and LY294002 (a specific PI3K inhibitor). Serum hormone levels (17 β-estradiol, follicle stimulating hormone, luteinizing hormone, progesterone, and testosterone) were measured by enzyme linked immunosorbent assay, and insulin resistance (IR) was assessed using the homeostasis model assessment of IR. Ovarian tissues were stained with haematoxylin and eosin for pathological and apoptosis examination. Expression levels of key transcriptional regulators and downstream targets, including IRS1, PI3K, protein kinase B (AKT), GLUT4, and PTEN, were measured via reverse transcription polymerase chain reaction and Western blot, respectively. RESULTS: The PCOS group showed impaired ovarian morphology and function. Compared with the PCOS group, curcumin treatment exerted ovarioprotective effects, down-regulated serum testosterone, restored IR, inhibited inflammatory cell infiltration in ovarian tissues, decreased IRS1, PI3K, and AKT expressions, and up-regulated GLUT4 and PTEN expressions in PCOS rats (P<0.05 or P<0.01). In contrast, IRS1, PI3K, AKT, and PTEN expression levels were not significantly different between PCOS and curcumin+LY294002 groups (P>0.05). CONCLUSION The beneficial effects of curcumin on PCOS rats included the alteration of serum hormone levels and recovery of morphological ovarian lesions, in which, PTEN, a new target, may play a role in regulating the IRS1/PI3K/GLUT4 pathway.
Animals ; Female ; Humans ; Rats ; Cell Proliferation ; Curcumin/therapeutic use* ; Follicle Stimulating Hormone ; Glucose ; Hyperandrogenism ; Insulin Receptor Substrate Proteins/metabolism* ; Insulin Resistance ; Ovarian Cysts ; Ovarian Neoplasms ; Phosphatidylinositol 3-Kinase/metabolism* ; Phosphatidylinositol 3-Kinases/metabolism* ; Polycystic Ovary Syndrome/drug therapy* ; Proto-Oncogene Proteins c-akt/metabolism* ; Rats, Sprague-Dawley ; Testosterone

OBJECTIVE: To observe the effect of electroacupuncture (EA) on protein expressions of suppressor of cytokine signaling 3 (SOCS3) and insulin receptor substrate-1 (IRS-1) in hypothalamus and morphology of pancreas islet in Zucker diabetic fatty (ZDF) rats, and to explore its possible mechanism on improving plasma glucose and insulin resistance of type 2 diabetes mellitus (T2DM). METHODS: Twelve SPF male ZDF rats were selected and fed with high-fat diet for 4 weeks to establish the T2DM model, after modeling, the rats were randomly divided into a model group and an EA group, 6 rats in each one. Besides, 6 SPF male Zucker lean rats were selected as a blank group. In the EA group, EA was applied at "Pishu" (BL 20), "Weiwanxiashu" (EX-B 3), "Zusanli" (ST 36) and "Sanyinjiao" (SP 6), with continuous wave, 15 Hz in frequency, 2 mA in intensity, once a day, 20 min each time, 6 times a week for 4 weeks. The fasting plasma glucose (FPG) was measured before and after intervention. The serum level of fasting insulin (FINS) was measured by radioimmunoassay, and the homeostasis model assessment of insulin resistance index (HOMA-IR) was calculated; the morphological change of pancreas islets was observed by HE staining; the protein expressions of SOCS3 and IRS-1 in hypothalamus were detected by Western blot. RESULTS: Before intervention, compared with the blank group, FPG in the model group and the EA group was increased (P<0.01). After intervention, compared with the blank group, FPG, serum level of FINS and HOMA-IR were increased (P<0.01), the protein expression of SOCS3 was increased while IRS-1 was decreased in the hypothalamus in the model group (P<0.01). Compared with the model group, FPG, serum level of FINS and HOMA-IR were decreased (P<0.01), the protein expression of SOCS3 was decreased while IRS-1 was increased in the hypothalamus in the EA group (P<0.01). In the model group, the shape of pancreas islets was irregular, the area of pancreas islets and the number of islet β cell nuclei were decreased, the nuclei of islet β cell was compensatory enlargement. In the EA group, the shape and the area of pancreas islets and the number of islet β cell nuclei were improved, the compensatory increase of islet β cell nuclei was alleviated compared with the model group. CONCLUSION Electroacupuncture can reduce the fasting plasma glucose, improve the morphology of pancreas islets, and alleviate the insulin resistance in ZDF rats. The mechanism may relate to the down-regulation of SOCS3 and up-regulation of IRS-1 in the hypothalamus, and improving the function of hypothalamus in regulating peripheral glucose metabolism.
Acupuncture Points ; Animals ; Blood Glucose/metabolism* ; Diabetes Mellitus, Type 2/therapy* ; Electroacupuncture ; Hypothalamus/metabolism* ; Insulin Receptor Substrate Proteins/metabolism* ; Insulin Resistance ; Male ; Pancreas/metabolism* ; Rats ; Rats, Zucker ; Suppressor of Cytokine Signaling 3 Protein/metabolism*

OBJECTIVE: To investigate the effect CD36 deficiency on muscle insulin signaling in mice fed a normal-fat diet and explore the possible mechanism. METHODS: Wild-type (WT) mice and systemic CD36 knockout (CD36^-/-) mice with normal feeding for 14 weeks (n=12) were subjected to insulin tolerance test (ITT) after intraperitoneal injection with insulin (1 U/kg). Real-time PCR was used to detect the mRNA expressions of insulin receptor (IR), insulin receptor substrate 1/2 (IRS1/2) and protein tyrosine phosphatase 1B (PTP1B), and Western blotting was performed to detect the protein expressions of AKT, IR, IRS1/2 and PTP1B in the muscle tissues of the mice. Tyrosine phosphorylation of IR and IRS1 and histone acetylation of PTP1B promoter in muscle tissues were detected using co-immunoprecipitation (Co-IP) and chromatin immunoprecipitation (ChIP), respectively. RESULTS: CD36^-/- mice showed significantly lowered insulin sensitivity with obviously decreased area under the insulin tolerance curve in comparison with the WT mice (P < 0.05). CD36^-/- mice also had significantly higher serum insulin concentration and HOMA-IR than WT mice (P < 0.05). Western blotting showed that the p-AKT/AKT ratio in the muscle tissues was significantly decreased in CD36^-/- mice as compared with the WT mice (P < 0.01). No significant differences were found in mRNA and protein levels of IR, IRS1 and IRS2 in the muscle tissues between WT and CD36^-/- mice (P>0.05). In the muscle tissue of CD36^-/- mice, tyrosine phosphorylation levels of IR and IRS1 were significantly decreased (P < 0.05), and the mRNA and protein levels of PTP1B (P < 0.05) and histone acetylation level of PTP1B promoters (P < 0.01) were significantly increased as compared with those in the WT mice. Intraperitoneal injection of claramine, a PTP1B inhibitor, effectively improved the impairment of insulin sensitivity in CD36^-/- mice. CONCLUSION CD36 is essential for maintaining muscle insulin sensitivity under physiological conditions, and CD36 gene deletion in mice causes impaired insulin sensitivity by up-regulating muscle PTP1B expression, which results in detyrosine phosphorylation of IR and IRS1.
Animals ; Gene Deletion ; Histones/genetics* ; Insulin ; Insulin Receptor Substrate Proteins/metabolism* ; Insulin Resistance/genetics* ; Membrane Cofactor Protein/genetics* ; Mice ; Mice, Knockout ; Muscles/metabolism* ; Phosphoric Monoester Hydrolases/metabolism* ; Protein Tyrosine Phosphatase, Non-Receptor Type 1/metabolism* ; Proto-Oncogene Proteins c-akt/metabolism* ; RNA, Messenger/metabolism* ; Receptor, Insulin/metabolism* ; Tyrosine/genetics* ; Up-Regulation

OBJECTIVE: To study the expression of tumor associated vascular insulin receptor (TVIR) in colorectal cancer with or without metabolic syndrome (MS) and its relationship with the pathological features of colorectal cancer. METHODS: The expression of TVIR in 220 colorectal cancer specimens was detected by tissue microarray and immunohistochemistry. The relationships between the expression of TVIR and the pathological features (pathological subtypes, histological grade, invasion depth, lymph node metastasis and TNM stage) of colorectal cancer with/without MS were analyzed. RESULTS: The insulin receptor expression was observed in colorectal cancer tissue or border area between cancer and normal tissue, but not in normal intestinal tissue. The high-expression rates of TVIR in MS group was remarkably lower than that of non-MS group (21.6%vs. 41.0%, CONCLUSIONS s: High-expression of TVIR is associated with aggressive pathological features such as invasion, lymph node metastasis and high TNM stage of colorectal cancer, especially for those patients without MS. TVIR could be a useful biological marker for prognosis of colorectal cancer.
Biomarkers, Tumor/genetics* ; Colorectal Neoplasms/physiopathology* ; Gene Expression Regulation, Neoplastic ; Humans ; Neoplasm Staging ; Prognosis ; Receptor, Insulin/genetics*

BACKGROUND: Dysregulation of hepatic glucose production (HGP) contributes to the development of type 2 diabetes mellitus. Telmisartan, an angiotensin II type 1 receptor blocker (ARB), has various ancillary effects in addition to common blood pressure-lowering effects. The effects and mechanism of telmisartan on HGP have not been fully elucidated and, therefore, we investigated these phenomena in hyperglycemic HepG2 cells and high-fat diet (HFD)-fed mice.METHODS: Glucose production and glucose uptake were measured in HepG2 cells. Expression levels of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase α (G6Pase-α), and phosphorylation levels of insulin receptor substrate-1 (IRS-1) and protein kinase C ζ (PKCζ) were assessed by western blot analysis. Animal studies were performed using HFD-fed mice.RESULTS: Telmisartan dose-dependently increased HGP, and PEPCK expression was minimally increased at a 40 μM concentration without a change in G6Pase-α expression. In contrast, telmisartan increased phosphorylation of IRS-1 at Ser302 (p-IRS-1-Ser302) and decreased p-IRS-1-Tyr632 dose-dependently. Telmisartan dose-dependently increased p-PKCζ-Thr410 which is known to reduce insulin action by inducing IRS-1 serine phosphorylation. Ectopic expression of dominant-negative PKCζ significantly attenuated telmisartan-induced HGP and p-IRS-1-Ser302 and -inhibited p-IRS-1-Tyr632. Among ARBs, including losartan and fimasartan, only telmisartan changed IRS-1 phosphorylation and pretreatment with GW9662, a specific and irreversible peroxisome proliferator-activated receptor γ (PPARγ) antagonist, did not alter this effect. Finally, in the livers from HFD-fed mice, telmisartan increased p-IRS-1-Ser302 and decreased p-IRS-1-Tyr632, which was accompanied by an increase in p-PKCζ-Thr410.CONCLUSION: These results suggest that telmisartan increases HGP by inducing p-PKCζ-Thr410 that increases p-IRS-1-Ser302 and decreases p-IRS-1-Tyr632 in a PPARγ-independent manner.
Animals ; Blotting, Western ; Diabetes Mellitus, Type 2 ; Diet, High-Fat ; Ectopic Gene Expression ; Glucose ; Glucose-6-Phosphatase ; Hep G2 Cells ; Insulin Receptor Substrate Proteins ; Insulin ; Liver ; Losartan ; Mice ; Peroxisomes ; Phosphoenolpyruvate ; Phosphorylation ; Protein Kinase C ; Protein Kinases ; Receptor, Angiotensin, Type 1 ; Receptor, Insulin ; Serine